Once compression has been applied to the pixels in all
the frames in a video, you end up with something called a
bitrate or data rate—the amount of data required to store
all the compressed data for each frame over time, usually
measured in kilobits or megabits per second. In general,
the higher the bitrate, the higher the video quality—and
therefore, the more storage required to hold the file and
greater the bandwidth required to deliver the stream. The
opposite is true of lower bitrate files, as shown in Figure 4,
where the lower bitrate quality is worse than the higher
bitrate version. Many other factors, including the quality
of the original source content and any preprocessing
filters applied will determine the final quality of the
compressed or encoded file.

Live vs. VOD Encoding

AWS Elemental compression products are divided
into two different categories—live encoders and video-on-demand (VOD) encoders. Live encoders take a live
video signal and encode it for immediate delivery, in
use cases such as a live concert or sporting event, or for
traditional broadcast channels. And while live encoders
are limited to analyzing and encoding the content in
real time, VOD encoders that use file-based media
sources and are not restricted to processing the content
in real time. VOD encoders may take multiple passes
at the video, analyzing it for motion and complexity—
explosions in an action movie require more effort to
encode than talking-head presentations, for instance.

Figure 4. See the difference in image quality between a high-bitrate file at the topand the low-bitrate file at the bottom.